1. Field of the Invention
The present invention relates to an image generation device and an information storage medium for generating an image as seen from a given viewpoint within an object space.
2. Description of Related Art
An image generation device is known in the art for disposing a plurality of objects within an object space, which is a virtual three-dimensional space, and generating an image as seen from a given viewpoint within that object space, making it highly popular for enabling players to experience a virtual reality. An example of this is an image generation device that enables players to enjoy a racing-car game, where each player manipulates a racing car to cause it to run within the object space and compete against other racing cars manipulated by other players, to enjoy this three-dimensional game.
With such an image generation device, it is desirable that the players can readily identify which player is manipulating which moving body (such as a racing car). Another subject of technical concern is to improve the feeling of a virtual reality that the players experience. One method that could be considered for identifying which player is manipulating which moving body is to display player identification images formed of written labels, superimposed on the moving bodies. For example, a moving body manipulated by a first player could have the written label xe2x80x9c1Pxe2x80x9d attached to it and a moving body manipulated by a second player could have the written label xe2x80x9c2Pxe2x80x9d attached to it. Alternatively, the players"" names could be attached to the corresponding moving bodies.
However, it is difficult for the players to immediately identify which players are manipulating which moving bodies. In addition, written labels such as xe2x80x9c1Pxe2x80x9d and xe2x80x9c2Pxe2x80x9d make it impossible for the players to become emotionally involved with the moving bodies, and thus it is not possible to increase the feeling of virtual reality experienced by the players.
It is also preferable that the player can easily and distinctly recognize which player is manipulating which moving body, whatever the current state of the game.
Note that techniques of utilizing photographed face images of the players in a game have already been disclosed in, for example, U.S. Pat. No. 4,710,873, U.S. Pat. No. 5,553,864, Japanese Patent Application Laid-Open No. 6-165874, Japanese Patent Application Laid-Open No. 6-165879, and Japanese Patent Application Laid-Open No. 6-176131. Techniques relating to texture mapping are disclosed in U.S. Pat. No. 5,561,746 and the like. In addition, techniques for making visible a marker that follows a moving body, even if it is hidden from the current field of view, are disclosed in Japanese Patent Application Laid-Open No. 7-8632 and the like.
The present invention was devised in the light of the above described technical concerns and has an object thereof the provision of an image generation device and information storage medium that simplify the recognition of an object such as a moving body, and also increase the feeling of a virtual reality.
To solve the above described technical concerns, the present invention relates to an image generation device for generating an image at a given viewpoint within an object space, comprising:
means for capturing an image acquired by an image acquisition means;
means for mapping a captured image onto an object;
means for modifying the perspective of the captured image, in accordance with whether the object on which the captured image is mapped is far or near; and
means for generating an image at a given viewpoint within an object space.
This aspect of the invention causes the display of an object on which a captured image is mapped. The perspective thereof is modified in accordance with whether the object is far away or near. This makes it possible to simplify the recognition of such an object, even when it ought not to be possible to recognize the captured image because the object is too far away, by way of example.
Note that the determination of whether an object bearing a captured image is far away or near could be based on the distance between the viewpoint position and that object, by way of example.
In a second aspect of the present invention, the perspective is modified in such a manner that, when the object on which the captured image is mapped is far away, the object is made to appear to be nearer than the actual position thereof. This makes it possible to increase the degree of resolution of the captured image, thus making it possible for the player to easily recognize the details of the captured image, even when the object bearing the captured image is far way.
In a third aspect of the present invention, the perspective is modified in such a manner that, when the object on which the captured image is mapped is near, the object is made to appear to be farther away than the actual position thereof. This makes it possible to prevent a captured image from being displayed too big when the object bearing that captured image is near, which would make it difficult for the player to recognize other images.
In a fourth aspect of the present invention, the perspective is modified by varying a scaling factor of the object on which the captured image is mapped. This enables the perspective to be modified by a simple process.
In a fifth aspect of the present invention, when the object on which the captured image is mapped is behind another object, an image of the object is generated as if appearing in front of the other object. Thus, when an object on which a captured image is mapped is hidden by another object such as an obscuring object, the captured image is visible through the obscuring object. As a result, the player can easily recognize the details of captured images, even when the map of the virtual reality has many obscuring objects.
In a sixth aspect of the present invention, an image of the object is generated as if appearing in front of the other object, by increasing a priority assigned for hidden-surface removal to the object on which the captured image is mapped. In other words, the ordinary method of hidden-surface removal would not display an object bearing a captured image when that object is behind an obscuring object. However, by increasing the priority for hidden-surface removal, that object can be made to appear as if in front of the obscuring object, enabling the player to recognize the details of the captured image.
In a seventh aspect of the present invention, the object on which the captured image is mapped is any one of a moving body that is moving within an object space and an object that follows the moving body: and the captured image is an identification image for identifying a player who is manipulating that moving body. This makes it possible to utilize a captured image as an image for identifying a player who is manipulated a moving body, so that all the players can easily and distinctly recognize which player is manipulating which moving body.